Patent GB-190306493-A (GB)
Title: Improvements in and relating to Electric Metering Systems
Inventor: CAROLAN EDGAR ALFRED
Filed: 1903-03-20
Granted: 1904-02-25
Abstract: 6493. Carolang E. A., [General Electric Co.]. March 20. Energy meters.-An energy meter is used with automatic switching apparatus for connecting its pressure circuits to the supply mains only when the power transmitted is above or below a certain limit, so that the energy supplied is registered only in these conditions. The invention is intended particularly for polyphase alternating systems, and is described as applied to a three-phase threewire system, with an ordinary induction motor meter. The two pressure circuits of this meter are closed or opened by an electromagnetic switch 74, Fig. 1, operated by passage of current from either of two contacts 26, 27 and the movable arm 24 of an electrodynamometer, connected in the supply mains. The arm 24 is freed from the contacts 26, 27 in the intervals of action of an electromagnet 42, which is periodically excited by current from an automatic switch of any form, such as that shown in Fig. 2. The three-phase electrodynamometer, Fig. 1, has two pressure coils carried by a vertical axle in the fields of two main-current electromagnets. Each electromagnet has two main coils 8, 9, carried on poles which project inward from a laminated iron rectangle 10. A laminated iron cylinder is supported within each pressure coil by cross-bars attached to the iron rectangle. The iron rectangles are supported by pillars and brackets 5, 6 on a back plate. The pressure coils and the contact arm 24 are connected by three spirals to the supply mains, and the turning of the axle is controlled by a spiral spring attached to a torsion bead 41, which is adjusted so that the arm 24 stands between the contacts 26, 27 when the prescribed power is passing. The contact arm 24 is periodically clamped against the underside of a stationary non-conducting plate 51 by a non-conducting arm, which is pivoted at 44, and is connected by a spring to the pivoted armature lever 43 of the electromagnet 42. At the same time the two contact springs 26, 27, carried by the armature lever 43, are pressed up to the plate 51, or against the contact arm 24 if this intervenes. The electromagnetic switch 74 has a cross-shaped pivoted armature, movable by four electromagnets 70, which are connected in pairs to the contacts 26, 27. Its contacts are arranged so that in one position it closes the pressure circuits of the energy meter, and in either extreme position it opens the circuit of the pair of electromagnets 70 which have moved it to such position. The automatic make-and-break switch, Fig. 2, has stationary and movable carbon contact cylinders 59, 58. The movable contact 58 is carried by a lever 57, which is pivoted on an armature lever 56, and is also connected to this by a spring. The armature lever 56 is pivoted between the poles of an electromagnet 53 ; its downward turning movement is limited by a stop 67. The lever 57 is connected by a link and a lever 61 to the plunger of a dash-pot 63, which retards downward movement of the parts by gravity, but permits free upward movement when the electromagnet 53 is excited. A stop 65 limits the upward movement of the lower end of the lever 57, to separate the contacts 58, 59. The electromagnet 53 is connected in series with the contacts 58, 59 and the electromagnet 42, Fig. 1, between two supply mains ; when contact is closed at 58, 59, the movable parts are thrown up by the electromagnet 53, and contact is broken, whereupon they fall slowly until contact is again made.